Will you be fishing for Brown Trout in the Taieri River in 2040?

Monday 25th March 2019

The advent of extreme and swift climate change has led society to ask questions about the future not previously considered as serious considerations.

Water clarity is vital if aquatic organisms (including fish) are able to locate food regularly (photo: Barry Kelk)
Water clarity is vital if aquatic organisms (including fish) are able to locate food regularly (photo: Barry Kelk)

Ten days ago the Year 13 Agribusiness class headed out to test the waters of the Taieri River armed with specialist environmental science equipment and the experience of Geoff Avis, Head of Science, himself a chemist and a geologist. After a fascinating introduction to the Taieri flood plain history from the Three Mile Hill viewpoint, we headed out to the Glen, Outram to begin testing at the first of seven sites. Every student had the opportunity during the day to use each piece of equipment and record the data for the rest of the class. 

The overall aim of the yearly project is to track the health of the river by testing numerous parameters that include dissolved oxygen levels, pH, temperature, chlorophyll-a levels, E.coli bacteria, nitrates, phosphates, clarity and salinity. With this growing body of data, one is able to consider the effects of climate change (now and in the future) and compare these data with the parameter requirements of the Brown trout as the (almost?) apex predator in that ecosystem. With late March water temperatures of around 17.5 degrees celcius at two sites and the knowledge that Brown trout can only spawn in temperatures 11 degrees and below in June, one can begin to imagine a future where this 150 - year old introduced species is no longer able to reproduce and survive in our rivers. 

Whilst the water-testing and sample collection is relatively easy (and fun) to accomplish, data analyses and interpretation is an entirely different matter. Students are now trying to make sense of the data by noting any obvious trends and statistically significant site parameter variations in order to produce a report about the long-term sustainability of the fish Otago locals love to lure! 

(My heartfelt thanks to the boys and girls for their excellent involvement and attitude throughout the day, to Geoff Avis for his patient instruction and assistance and to Andrew Parkin for helping out along the way)

Water clarity is vital if aquatic organisms (including fish) are able to locate food regularly (photo: Barry Kelk)
How low can you go! Water clarity is measured by using a clarity tube; at a certain point the black disc on the magnets 'disappears' from view and a clarity measurement is made...
A photographer's dream shot...
'Chambo' and Charles measuring the water flow rate at site No. 3
Testing temperature, pH, dissolved oxygen levels, salinity and other parameters using the YSI multimeter, whilst Nick Chamberlain fishes in the background! (photo: Barry Kelk)
Masters of Teaching and Learning student, Andrew Parkin, keeps an eye on the water-testing gear!
After a long day of water testing, we enjoyed an ice-cream at Brighton Beach before heading back to the Colleges (photo: Barry Kelk)
Time for a rest and photoshoot - da boys...